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What size pipe and pipe layout?

I ordered a 1" Febco PVB that will be coming off a well pump of unknown size at the moment (well digging and pump pending). What size pipe should I in turn run to the heads to avoid 'waterhammer' e.t.c.? I'm thinking about 1.25" sched. 40 (i'll use no less for strength reasons) will do the trick and keep the GPM at a descent pressure. In this case, if my pump provides around 40 psi, what pressure can I expect at the heads?

Also, about pipe layout, i'm a bit confused. I've been told that to keep pipe turns to a minimum to keep pressure up to par. Is there a good link that shows a nice layout of pipe design going to the heads e.t.c.? I understand there will be some pressure loss with friction loss, but more concerned of just getting the right/adequate pressure to the heads. Quick help appreciated. Thanks

You need to see what kind of water volume and recovery rate you will have when your well is setup before determining the pipe size. Also how long are your farthest runs from the well.

Remember that the depth of your well also counts for your friction loss calculations. Your 40psi after friction losses might bring you down close to 20psi. WHich is pushing it if your planning on using rotors. Your well guy needs to know that your using it for irrigation and that water volume and recovery rate is key. As for the PSI, this can be configured with the size pump you use.

You've got to start by figuring out what the expected GPM of the system is going to be. Once you know the expected GPM, you can use tables to determine what pipe size is needed to keep water velocity below 5-7fps. You will also have to size it so that friction loses are minimized so that you still have about 30psi at the spray heads. The other think to watch is that you make sure there isn't more that about a 20% pressure difference between the spray heads (i.e. the pipe must be sized such that friction losses between the first head and last head in a run of pipe are less than 20% of the pressure needed at the sprary heads).

As for keeping pipe turns to a minimum, there are charts you can find that will give you the friction losses for various fittings (expressed as an equivalent foot of pipe). It's not a matter of finding a "nice layout of pipe design", just don't introduce any extra turns when one is not needed. I think you will find that a 90 degree elbow with be equal to adding about 1-2 ft of pipe. Take this additional length into account when you size the pipe and I think you should do ok. Other examples of minimizing elbows would be that if you must go around an obstical, you will use less pipe and fewwer elbows if you go around the obstical in a V shape rather than a box shape.

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by aquamatic</i>
<br />You need to see what kind of water volume and recovery rate you will have when your well is setup before determining the pipe size. Also how long are your farthest runs from the well.

Remember that the depth of your well also counts for your friction loss calculations. Your 40psi after friction losses might bring you down close to 20psi. WHich is pushing it if your planning on using rotors. Your well guy needs to know that your using it for irrigation and that water volume and recovery rate is key. As for the PSI, this can be configured with the size pump you use.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

How do you determine the water volume and recovery rate anyway? Is there a formula or something? Thanks.

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by aquamatic</i>
<br />This is information that your pump guy would tell you. This can only be determined after you drill. Its based on depth and the water column recovery rate
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I guess I definitely have to get the well dug first then. My furthest pipe runs will be less than 100' for now, so as long as I don't have too many unnecessary bends, I should be golden right? Assuming I have a proper sized pump for my biggest zone.

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by aquamatic</i>
<br />Defintely let him know what you are trying to accomplish- Tell him you would like to get a minimum of 6-8 recovery at atleast 30-40 psi of pressure when selecting pump
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Will do. On another topic, do you guys seal threaded risers e.t.c. with pvc cement or teflon or just thread them in to their female counterparts for a good seal? Just wodering.